Frequently Asked Questions

Our progressive packs are our signature product. These leaf springs are designed with one thing in mind; performance. Instead of employing three of four leaf, two stage design as is typical of an OEM spring they consist of several thin flexible leaves (as many as twelve per pack depending on the application!), resulting in a multistage spring with a very forgiving street ride, even in the heaviest trucks. They do well in daily drivers, pre runners and rock crawlers alike! If you do a lot of towing or hauling with your vehicle we recommend we recommend you look to our Expedition Pack springs, as the Progressive Pack springs are not designed with heavy loads in mind. For the occasional load or tow vehicle they can be combined with a cantilever air bag set up for the ultimate combination of ride, flex and load carrying capacity. They are hand crafted by our skilled technicians on our premises.  High quality North American components are used in every single leaf spring we manufacture. From the simple rivet, to the complex steel composition, no detail is overlooked. Atlas leaf springs include anti-friction pads inserted between each leaf for a smoother ride and quiet operation, full military-wrapped spring eyes for safety and superior durability, riveted rebound bolt clips, and a premium paint finish is our standard.

A standard pack is a lift spring modeled after the OEM leaf spring, maintaining load bearing characteristics similar to their factory counterparts. They generally consist of two stages and tend to lead to a rough ride very quickly as lift heights go up.

Our Expedition packs are geared towards the off road enthusiast that requires a little of both worlds; flexibility, and load carrying capacity all in one.  Essentially two springs in one, we designed this style of leaf spring as a progressive two stage pack. All the great and innovative features of an off road Progressive Pack are included with this design, but we add an additional load carrying 2nd stage that helps for towing and hauling.

The Heavy Duty Pack is a spring designed for the fullsize truck owner who's vehicle is used and abused. Not to be confused with the Expedition Pack, the HD Pack is a rough riding, tough as nails spring that can be tailored to the customer's uses. Good applications for HD springs are dedicated welders, work trucks, goosenecks and construction vehicles that see conditions beyond what the manufacturer intended.

Atlas' Race pack springs are designed for maximum performance in an off road environment  while enduring punishment you can throw at it. Essentially our Progressive Pack design turned up a notch with all of the things about it that make it a quiet, smooth riding daily driving spring removed, the Race Pack isn't designed for a street driven truck.

If you're asking this, the answer is probably no. A race pack spring is a very soft performance spring with a small, durable polyurethane bushing. A race pack is designed to deliver maximum performance and durability in extreme off road conditions, but will deliver poor handling and a jarring ride on the street. Race pack is recommended for trail dedicated rock crawlers, prerunners, and competition vehicles. Even if you drive your truck to the trailhead you may choose to go with our "progressive pack" option.

There are two preferred points to measure vehicle ride height. Both measurements should be taken on a level flat surface. One is at the center of the fender well to the ground.The other is at the bump stop to the axle housing or frame.

The leaf spring dates back to medieval times and is one of the simplest and oldest forms of spring technology. Early leaf springs used leather instead of the metal design we are familiar with today. Modern leaf springs use a series of steel plates of varying length and thickness, known as leaves, bound together in a pack. Some suspensions use a mono leaf design, which only uses one leaf in place of a pack. The number and thickness of these leaves are what dictate spring rate and load capacity. The overall length has an effect on ride quality, while the width of the leaf and whether it is mounted inboard or outboard all have an effect on stability.

Because of their tapered shape, leaf springs-including mono leaves are progressive-rate springs. This means they grow stiffer the more they are compressed, which makes them superior for heavy load carrying than so-called single- or linear-rate (i.e., coil) springs. Leaf springs are also modular, meaning that if you desire a change in ride height or capability, all you have to do is add or remove leaves. The higher-quality packs will use multiple, thinner leaves to reduce friction. This stacking of leaves also makes for a more durable product because one leaf isn't holding the entire load, and if one were to break, chances are that the others will hold together long enough to get you home.

While all leaf springs are progressive-rate, some spring packs are two-stage. Two stage spring packs keep the progressive pack, but add an overload spring underneath to gain maximum load rating while retaining good ride characteristics when unloaded. These packs are typically used in the rear of pick up trucks.

Although the design of a leaf pack itself is fairly complex, overall it is the simplest form of suspension design because the leaf packs both control and locate the axle without the need for control arms. Leaf springs also have the benefit of better stability, especially when hauling or towing at or near the rated maximum, by reducing sway and spreading out the load over a greater portion of the chassis.

Besides supporting the weight of a vehicle, the leaf springs control the ride height and keep the tires in contact with the road. Springs also affect alignment angles and are the most important components in controlling the "feel" of a vehicle's suspension system.

When measuring your springs, there are only six measurements you need to worry about:

A. Along the surface of the main leaf from eye of front bushing to center pin (A.)

B. Along the surface of the main leaf from center pin to rear eye of the leaf spring (B.)

C. The spring arch is measured from the top surface of the main leaf at the center pin to the centerline of the spring eyes (C.)

D. Pack thickness

E. Center to center of spring eyes

F. Bushing dimensions

See illustration for details.

Measure the dimensions of the leaf spring (see "What is the proper way to measure my leaf spring?") and count how many leafs in the spring pack then compare your measurements with the specs in our OEM leaf spring table.

Spring rate is the amount of force that is required to compress, extend, or twist a spring one inch. Usually spring rate is measured in pounds per inch. Load rate is a is the amount of weight the spring is designed to carry at a certain height.

An Add-A-Leaf is a extra leaf added to a leaf spring pack. Add leafs are installed to increase vehicle carrying capacity or to create a firmer ride. They are also used to lift vehicle ride height. The number or leafs added and the thickness of the leafs directly determine the percentage of ride quality/height change.

An overload is a second stage leaf spring which is engaged when load is applied. It is usually located at the bottom of a leaf spring assembly. Most of the time it is tapered. Top mount overloads are auxiliary overloads located at the top of a leaf spring assembly.

There are several reasons to replace leaf spring:

1. Worn or sagging springs - Weak springs lower the chassis height of a vehicle, resulting in premature tire wear and poor handling characteristics.
2. Sagging when loaded - Vehicles used for family transportation, RV's, works trucks, or sales fleets can benefit from upgrading to heavier duty leaf springs
3. Broken original springs - Certain vehicles have been known to have a very high failure rate of broken springs.

There is no standard life expectancy for leaf springs. In general, leaf springs on smaller lighter weight vehicles tend to last longer then leaf springs on heavier full-sized vehicles applications. To determine when coil springs need to be replaced have the springs inspected and the vehicle ride height checked by a trained professional.

Atlas Leaf Springs are manufactured to more exact standards and the material is far superior then that of imported spring steel with the exception of springs made in Canada, or Mexico. In the case of springs, you really do get what you pay for. Our springs ride better, flex better, handle loads better and our fully customizable!

Re-arching is a process of re-curving each leaf spring to original or custom specifications. Once the springs are individually re-arched they are then heat set. Heat setting is done by heating the spring to a specific temperature for a specific time.

The most common method of leaf spring inspection is checking the vehicle ride height. Measure! Don't rely on eyesight alone! This method will only catch the extreme cases of spring sag or leaning. In addition to checking ride height, look for these signs, which also indicate the leaf spring requires attention:

Examine each spring for stress cracks, missing leafs, or shiny spots between leafs.

Damaged bushings or bump stops on the frame.

Front end of vehicle nose dives when braking or vehicle sway. Spongy ride.

Vehicle that commonly carry extra weight, resulting in un-level condition most of the time (family transportation, work trucks, and sales fleets).

Bushings are used in many locations on the vehicle suspension system. Most bushings are made with natural rubber. However, in some cases, urethane compounds may be used. Bushings made of natural rubber offer high tensile (tear) strength and excellent stability at low temperatures. Natural rubber is an elastomeric material. Elastomeric refers to the natural elastic nature of rubber to allow movement of the bushing in a twisting plane. Movement is controlled by the design of the rubber element. Natural rubber requires no lubrication, isolates minor vibration, reduces transmitted road shock, operates noise free, and offers a large degree of bushing compliance. Urethane bushings will increase the performance handling characteristics of your vehicle. Urethane is a firmer material then rubber.

A. Measure the outer diameter of the rubber casing

B. Measure the inner diameter of the rubber casing

C. Measure the width of the rubber casing

D. Measure the width of the metal sleeve of the bushing if applicable

Then visit our OEM Bushing Table for more information

Polyurethane is a term used to describe a wide ranging family of elastomers (any compound exhibiting the characteristics of natural rubber; stretchy and elastic.). Poly meaning "many" and "urethane" the classification of the chemical structure. Polyurethane or urethane for short, is used as a solid cast material (bushings). Polyurethane can be as soft as a rubber band or as hard as plastic.

Bushings are the second most important component of your leaf springs only to the leaf spring itself. There are two types of bushings generally utilized for passenger vehicle leaf springs: rubber encased and polyurethane.

Polyurethane is very durable, but is stiff and and translates harsh vibrations from the road directly into the chassis of your vehicle. Depending on the vehicle you may never have to replace or service a polyurethane bushing for years. Polyurethane bushings will lead to a better handling but at the sacrifice of suspension flex and ride quality.

Rubber encased bushings are still durable, but will require repair or replacement every few years, depending on the vehicle weight and how hard it is driven. Rubber encased bushing equipped leaf springs will not handle as well as a polyurethane bushing, but will yield a vast improvement in ride quality. A rubber encased bushing acts as a pivot point for your leaf springs and can result in several hundred points of flex on an RTI ramp. Atlas Suspension recommends rubber bushings for all street driven vehicles and advocates for rubber bushings in all but the most abused offroad vehicles. We feel the benefits of the rubber encased bushing outweigh the drawbacks. Most off road vehicles are not designed to handle like track cars, and a good sway bar system will do wonders for handling while still taking advantage of the rubber bushing's inherit flex and ride quality. Rubber bushings are also cheap and easy to replace if they are torn or damaged. Atlas offers extra large bushings as an option on all of it's Atlas brand leaf springs and invites the customer the contact us with any questions.

3/8" - 30 ft. lbs

7/16" - 45 ft. lbs

1/2" - 65 ft. lbs

9/16" - 95 ft. lbs

5/8" - 125 ft. lbs

3/4" - 225 ft. lbs

7/8" - 325 ft. lbs

1" - 625 ft. lbs

There are two preferred points to measure vehicle ride height. Both measurements should be taken on a level flat surface. One is at the center of the fender well to the ground.The other is at the bump stop to the axle housing or frame.

When measuring your springs, there are only six measurements you need to worry about:

A. Along the surface of the main leaf from eye of front bushing to center pin (A.)

B. Along the surface of the main leaf from center pin to rear eye of the leaf spring (B.)

C. The spring arch is measured from the top surface of the main leaf at the center pin to the centerline of the spring eyes (C.)

D. Pack thickness

E. Center to center of spring eyes

F. Bushing dimensions

See illustration for details.

Measure the dimensions of the leaf spring (see "What is the proper way to measure my leaf spring?") and count how many leafs in the spring pack then compare your measurements with the specs in our OEM leaf spring table.

The most common method of leaf spring inspection is checking the vehicle ride height. Measure! Don't rely on eyesight alone! This method will only catch the extreme cases of spring sag or leaning. In addition to checking ride height, look for these signs, which also indicate the leaf spring requires attention:

Examine each spring for stress cracks, missing leafs, or shiny spots between leafs.

Damaged bushings or bump stops on the frame.

Front end of vehicle nose dives when braking or vehicle sway. Spongy ride.

Vehicle that commonly carry extra weight, resulting in un-level condition most of the time (family transportation, work trucks, and sales fleets).

A. Measure the outer diameter of the rubber casing

B. Measure the inner diameter of the rubber casing

C. Measure the width of the rubber casing

D. Measure the width of the metal sleeve of the bushing if applicable